Use vpx_sse instead of vpx_mse to compute SSE

Use vpx_sse instead of vpx_mse to compute SSE

Use vpx_sse and vpx_highbd_sse instead of vpx_mse16x16 and
vpx_highbd_8_mse16x16 respectively to compute SSE for PSNR
calculations. This solves an issue whereby vpx_highbd_8_mse16x16
was being used to calculate SSE for 10- and 12-bit input.

This is a port of the libaom CL
https://aomedia-review.googlesource.com/c/aom/+/175063
by Jonathan Wright <jonathan.wright@arm.com>.

Bug: webm:1819
Change-Id: I37e3ac72835e67ccb44ac89a4ed16df62c2169a7
(cherry picked from commit 7dfe343199381bddddc5eaa648e947876979b61b)